error message

Hi, I purchased a theme and the developer is not responding to emails… there is an error message on the front page of my site and I don’t know how to get rid of it – message says:

Fatal error: Call to undefined function wp_pagenavi() in /home/madinme1/public_html/wp-content/themes/neuethemesbasel11/Basel11/index.php on line 99

Can anyone help me with this? I’m not a coder, however I do follow instructions. Thanks in advance for your assistance.

Dale.